Do you need 10 great ECs to get into top colleges?

You will be fine.

Both my kids were accepted to elite colleges, and neither filled all the spots. I think my daughter had six.

My son had more at nine, but three were summer programs. Another was a student government position which didn’t take much time. The rest were deeper.

On a related note, both my kids used the additional information section to flesh out the activities whey were heavily involved in.